The present invention relates to a target detection method for a flying body provided with a search head, with the flying body rotating during its descending flight and scanning the area with its search head for possible targets, and wherein the geometric dimensions of the possible targets are determined in the direction of the scanning path (Y direction) and in the direction perpendicular to the scanning path (X direction) under consideration of the distance R between the flying body and the possible target, and the determined geometric dimensions are compared with corresponding stored values to detect the presence of a true target.
Such methods are known per se and may be employed in so-called target seeking projectiles. In this regard, see, for example, Flume, "Artilleriemunition: Bessere Wirkung im Ziel," Artillery Ammunition: Better Effect in the Target, Wehrtechnik Military Technology 1985, pages 112 to 120.
Target seeking projectiles or flying bodies are customarily ejected over the target area from a carrier projectile and then drop to the ground while rotating on a parachute. The rotation of the projectile results in the target area being scanned by a search head in the projectile. As soon as a target is detected, a projectile forming charge on board the target seeking projectile is detonated so that the formed projectile can then destroy the target.
In such a method, the target is detected, inter alia, by its geometric dimensions. Targets which exceed or fall below predetermined dimensions are identified as false targets and excluded.
The extent of a target in the X direction results from the number N of detector elements oriented in the X direction of the search head which emit an output signal corresponding to the target temperature (in the case of an infrared detecting search head). The spatial extent results from a predetermined imaging scale and considers the aperture angle .delta..alpha. of an element of a row of detectors as well as the distance R between the flying body (projectile) and the target according to the equation EQU X=N.multidot.R.multidot..delta..alpha. (1)
To determine the extent of the target in the scanning direction Y, the time T during which the search head scans or detects the target during one revolution is determined. The following then applies: EQU Y=T.multidot.V.sub.SC ( 2)
where EQU V.sub.SC =.omega..multidot.R.multidot.sin .phi.
and
.omega.=the angular velocity of the projectile,
R=the distance between the projectile and the target,
.phi.=the angle between the rotation axis and the symmetry axis of the projectile.
In the prior art arrangements the term .omega..multidot.sin .phi. is assumed to be constant. However, under real conditions, .omega. as well as .phi. are not constant in time.
Aerodynamic influences in particular, or incomplete opening of the autorotation parachute which causes the target seeking fuze or projectile to rotate, cause a reduction in the angular velocity .omega. or also a pendulum movement of the system which leads to fluctuations of .phi.. The consequences of a reduced angular velocity .omega. are lower rpm and scanning velocities V.sub.SC so that the target appears to be larger than it really is. Similar conditions apply for deviations of the angle .phi.. If the target seeking fuze or projectile performs larger pendulum movements in the Y direction, changes of .phi. during the searching process make the signature appear distorted.